This has already been pretty well answered. I would only add that it's important to remember that a star, which our sun is, is a massive fusion reactor. Stars are primarily composed of hydrogen and is also a star's fuel source, as hydrogen is consumed it produced other elements such as helium. In fact this is how many of the complex elements are produced, in the centers of stars. A star's lifespan is determined by its size and energy output, hotter larger stars consume go through their hydrogen faster than cooler small stars. A star's life comes to an end when it exhausts its hydrogen reserves and begins to consume heavier elements. In a star like our sun that results ultimately in the sun expanding into a red giant--which as others said won't happen for another several billion years. But this will ultimately result in the sun shedding its outer material and shrinking down into a white dwarf. Other stars, notably large ones (our sun is sort of small as stars go) which when they reach the end of their life explode releasing trillions of tons of stellar matter into the cosmos.
The earth, like the other planets in our solar system, came into existence from remnant matter from the formation of our sin. In the early days of our solar system soon after the sun formed there was what we call an accretion disc, a disc of material circling around the primitive sun. Over the course of millions of years matter moving and bumping into one another and gravity resulted in the formation of larger chunks of matter. Mass attracts mass, and so at one point there were possibly hundreds of planetoids circling the sun. Things smashing into one another, and so on. This is how our earth was born, and indeed the moon was likely formed very early in earth's life when a Mars sized planet smashed into early earth, resulting in tons of matter being flung into space, that's our moon. It's also likely that this is the reason we still have such a very active planetary core. The earth cooled, icy comets likely brought water, forming oceans. The earth's atmosphere would have probably been primarily carbon dioxide, fortunately early cellular life began producing oxygen--bad for other living things, but great for us.
The big bang doesn't have to do with the solar system. But the universe. The theory says that at the beginning of time the universe was a single point of insanely hot dense energy, and "exploded". Though that's a poor way of thinking of it, the universe expanded, very, very rapidly. The universe, in fact, is still expanding. Space itself is expanding.
Well in some cases the other planets are absolutely essential for life here on earth. Jupiter, being so big, protects us from a lot of the really dangerous comets and asteroids that frequently come zooming in from the outer solar system. Without the giant planets out there like Jupiter or Saturn we'd likely see a lot more action than we do--and that'd be really bad for life here on earth.
So we're in a pretty great position, we're in the right place from the sun so that liquid water can exist, we have an active core that means a magnetic field that protects us from most of the most harmful rays from the sun, we have a moon that helps keep much of our planet regulated, we have a pretty fantastic axial tilt that keeps our seasons basically mild, we have large outer planets that protect us from many of the dangers floating out at the edge of the solar system.
We got things pretty good on earth. It's a good planet to live on.
-CryptoLutheran
